These E-cigarettes let users inhale vapour laced with nicotine, but without breathing tobacco, tar or other associated harmful substances.

And they can do it in a flavour of their choosing.

This shopper was pleasantly surprised by the electronic alternative.

E-CIGARETTE CUSTOMER,

"I was expecting it to taste like the chewing gums you buy - the nicotine chewing gums. It didn't taste anything like that. Plus with the different flavours it just makes it a little bit more pleasant."

E-cigarettes are becoming big business and this company in London has been reaping the benefits.

JIM LACEY, CEO, SMOKE-NO-SMOKE UK,

"We started up one store in the United Kingdom a year last December. Since then we've now got seven stores open and we have contracts to open another twenty stores".

Now, according to euromonitor, the market for e-cigarettes will be worth $3bn in 2013. This is still dwarfed by the global tobacco industry with will be worth $720bn this year. However the market has come a long way; e-cigarettes sold less than $100m-worth in 2007. But there are clouds on the horizon. This is a market which is heavily reliant on Western consumers, and there are questions over whether it could soon burn out.

In emerging markets there has been very low take up.

For example the Indian market is only around $2m while China, which manufactures many of the e-cigarettes, has a negligible domestic market for domestic sales.